1. Historical versus Current Distribution. California slender salamanders
(Batrachosepsattenuatus) occur in two principal areas: along the
California coast and adjacent Inner Coast Ranges from north and east of Monterey Bay
(extreme western Merced, Monterey, and San Benito counties) northward to extreme
southwestern Oregon (south side of the Rogue River, Curry County; Yanev, 1978, 1980;
Leonard et al., 1993); and in the western foothills of the northern and central Sierra
Nevada, from Calaveras County north to at least Butte County (Hayes and Cliff, 1982;
Jockusch et al., 1998). Inner Coast Range populations extend as far north as
Tehama County (Jennings, 1982; Boundy, 2000). Isolated records of
Batrachoseps from the floor of California’s Central Valley (Stanislaus,
San Joaquin, and Yolo counties) probably represent California slender salamanders,
although confirmation from genetic analysis is lacking. Additionally, there are
isolated populations in Shasta County (north of California’s Central Valley) in the
Little Cow and Clipkapudi Creek drainages (Stebbins, 1985).

The Sierra Nevada
portion of the range is poorly defined, and some of the museum specimens currently
allocated to California slender salamanders on the basis of morphology may be
misidentified. Two similar-looking species approach or overlap the range of
California slender salamanders in the central Sierra Nevada: gregarious slender
salamanders (B. gregarius) range as far north as Mariposa County, just
south of the southernmost range limits for California slender salamanders; and Hell
Hollow slender salamanders (B. diabolicus) may be broadly sympatric
with California slender salamanders between El Dorado and Calaveras counties, although
the two have been found together at only one site (north slope of the American River;
Jockusch et al., 1998).

Populations of
California slender salamanders and the morphologically similar Gabilan Mountains slender
salamander (B. gavilanensis) narrowly (by a few hundred m to a few km) overlap
in geographic distribution along the southern border of the range of California slender
salamanders in Santa Cruz and San Benito counties (Yanev, 1978, 1980; Jockusch et al.,
2001).

2. Historical versus Current Abundance. Early reports (e.g., Stebbins, 1954a;
Anderson, 1960) and more recent fieldwork by R.W.H., D.B.W., and colleagues suggest that
California slender salamander population densities in the coastal portion of the range
remain high. Estimates of densities range from 4,470/ha (Contra Costa County;
Anderson, 1960, citing data from Hendrickson, 1954) to 17,290/ha on Red Rock Island in
San Francisco Bay (Anderson, 1960). Stebbins (1954a) reported that a Contra Costa
County population of California slender salamanders (presumably the same site studied by
Hendrickson, 1954) occurred at densities relative to ensatinas (Ensatinaeschscholtzii) of 7:1; he estimated the latter to occur at 170–200
adults/ac. This suggests a population density of 1,190–1,400/ac
(2,939–3,458/ha) for California slender salamanders.

3. Life History Features.

A. Breeding.
Reproduction is terrestrial.

i. Breeding migrations. Movements associated with reproductive activity are
virtually unknown for any species of Batrachoseps. However, Anderson (1960)
observed 69 adult California slender salamanders surface active during a heavy rain at
night on 26 October (San Francisco Bay area); nearly all were gravid females moving
uphill and across a road, a minimum distance of about 9 m. Coastal populations lay
eggs shortly after the onset of fall rains, generally in October–November
(Stebbins, 1951). Periods of oviposition for Sierra Nevada populations are unknown,
but likely later in the year (December–January).

i. Egg deposition sites. Females deposit eggs beneath rocks, logs, or other
objects, although the paucity of nests discovered in the field suggests that most females
are ovipositing underground (Burke, 1911; Storer, 1925; Myers, 1930b). Females
apparently abandon eggs to communal nests, although female association with eggs has been
observed (Snyder, 1923; Maslin, 1939). Storer (1925) described one nesting site as
consisting of 53 eggs found “under a plank in a moist, springy place near a brush
pile.” Maslin (1939) described finding a female in the act of egg laying; the
female “was in a small depression in damp soil beneath a strip of tin” in the
shade of a tree. Three other adult females occupied this depression, along with 74
eggs. Burke (1911) reported the discovery of 35 eggs (in groups of 21, 10, and 4)
under a log in a moist ravine, unattended by any adults. Sixty-eight eggs were
found in a small depression (ca. 25 mm diameter) beneath a board in late December in
Contra Costa County; three adult salamanders were present under the board as well, but
none was in contact with the egg cluster (R.F. Hoyer, personal communication).

C. Direct
Development. Mean incubation periods for lab-incubated eggs (at 13 ˚C) ranged
from 72–86 d (Jockusch, 1997a; Jockusch and Mahoney, 1997). Hatchlings have
been observed in late January to February (San Francisco Bay area), and in late December
at Walnut Creek (Contra Costa County) and St. Helena (Napa County; R.F. Hoyer, personal
communication).

D. Juvenile
Habitat. Maiorana (1976) found that juvenile California slender salamanders were
more likely than adults to be active under sub-optimal surface conditions.
Differential use of surface cover elements is unstudied, although juveniles often occur
under relatively smaller pieces of cover.

E. Adult
Habitat. Along the coast of northwestern California, California slender salamanders
are largely restricted to low elevation, coastal redwood forest (Bury and Martin, 1973;
Bury, 1983; Welsh and Lind, 1988). In southwestern Oregon, they are closely
associated with humid coastal mixed evergreen forests (Leonard et al., 1993).
Farther south, populations occur in a broader range of habitats, from moist coastal
forests to oak woodlands. Sierra Nevada records are principally associated with
pine-oak woodland and chaparral of the foothills (Block and Morrison, 1998), although
populations may extend onto the floor of the Central Valley along riparian corridors
(Hayes and Cliff, 1982). Ecological and behavioral aspects of water economy are
described by Wisely and Golightly (2003).

Individuals occur
under logs, bark, rocks, boards, and other surface cover, and in damp leaf litter
(Stebbins, 1985). Periods of surface activity correspond closely to the rainy
season (November–April/May for most of the range, later in moist, coastal
forests). Maiorana (1977a) observed salamanders dead and dying in the field in the
San Francisco Bay region during March and April; she attributed mortality to thermal
stress. Field body temperatures for salamanders found under surface cover ranged
from 2.2–15.8 ˚C (mean of 7.7 ˚C, n = 82; Feder et al., 1982; R.W.H.,
unpublished data).

F. Home Range
Size. Aside from longer movements associated with breeding activity, individuals
tend to remain within a small area over most of their lives. Anderson (1960) found
short-term movements averaging 1.5 m, and Maiorana (1978a) recorded movements to 2
m. There is a strong tendency for individuals to occupy the same cover objects over
several seasons; Hendrickson (1954) recaptured 59% of his marked animals under their
original cover.

G.
Territories. Unknown.

H.
Aestivation/Avoiding Dessication. Surface activity corresponds to moist surface
conditions, which for most of the range means a period of November–March/April,
with local differences related to elevation, slope exposure, and recent precipitation.
Surface activity is extended in some areas, such as those receiving daily on-shore
fog or in closed canopy redwood forests, where moist conditions prevail outside the rainy
season. In the San Francisco Bay area, surface activity begins in October and
extends to May (or June in favorable years). In the moist redwood forests of the
Santa Cruz Mountains, activity may occur in all months (Brame, 1959). During the dry
season, individuals apparently retreat underground, using old root channels, earthworm
burrows, or deep talus.

K. Interspecific
Associations/Exclusions. Over most of their range, California slender salamanders
are the only species of Batrachoseps present. Along the southern slopes of
the Santa Cruz Mountains, the ranges of California slender salamanders and
morphologically similar Gabilan Mountains slender salamanders (B.
gavilanensis) overlap, and they are locally sympatric (e.g., Hecker Pass on the
Santa Cruz-Santa Clara County line; Jockusch et al., 2001). In general, California
slender salamanders are found in more mesic and upland sites than the other
species. Habitat associations for California slender salamanders in the Sierra
Nevada are not well understood, and only a single area of sympatry with Hell Hollow
slender salamanders is known (Jockusch et al., 1998).

Maiorana (1978a)
suggested that differing patterns of fine-scale distribution between sympatric arboreal
salamanders (Aneideslugubris) and California slender salamanders were
due to differential cover use—arboreal salamanders prefer structurally diverse
microhabitats (e.g., rock piles) with larger openings and retreats relative to those
preferred by California slender salamanders. Further, she suggested that competition
with arboreal salamander for burrows, rather than prey availability, may limit the
density of Batrachoseps in some areas.

O. Predators.
Several workers document predation under conditions of captivity (e.g., Hubbard, 1903;
Storer, 1925; Stebbins, 1954a). Stebbins (1951) and Storer (1925) state that
arboreal salamanders feed on California slender salamanders, but details are not provided
and it is not possible to determine the prey species involved. The only unambiguous
records of predation in the wild we can locate are by sharp-tailed snakes
(Contiatenuis), Santa Cruz garter snakes (Thamnophisatratus; Stebbins, 1954a; Boundy, 1999), California giant salamanders
(Dicamptodonensatus; Bury, 1972; T. Burkhardt, personal communication),
and scrub jays (Aphelocomacoerulescens; Reaser, 1997b). Several
authors have suggested ring-necked snakes (Diadophispunctatus) as
likely predators, and captive individuals readily consume California slender salamanders
as well as other species of Batrachoseps (R.W.H., personal observations).
We regard screech owls (Otuskennicottii) as likely predators as well,
although this remains undocumented.

P. Anti-Predator
Mechanisms. The following behaviors have been documented: coiling, violent
thrashing (rapid coiling/uncoiling or “flipping” behavior),
immobility/crypsis, release of adhesive skin secretions, and tail autotomy (Hubbard,
1903; Storer, 1925; Brodie et al., 1974a; Garcia-Paris and Deban, 1995). Flipping
behavior may propel an individual salamander 10–20 cm where it may remain
motionless (Brodie et al., 1974a). Arnold (1982) reported that in a lab-staged
encounter between a California slender salamander and a garter snake, the salamander
prevented ingestion by looping its tail around the snake's head to form a knot.
Moreover, adhesive skin secretions released by the salamander caused the snake's jaw to
remain glued shut at least 48 hr later. The drab brown to reddish-brown dorsal
coloration often closely matches native substrates. Maiorana (1977b) reported that
tail break frequencies of adult California slender salamanders from a population near
Berkeley ranged from 28–48% annually, with an equal distribution between sexes.

S. Comments.
Until Yanev’s work (1978, 1980), California slender salamanders included several
other forms now recognized as distinct species: black-bellied slender salamanders
(B. nigriventris), gregarius slender salamanders, Hell Hollow slender
salamanders (B. diabolicus, in part), as well as the recently described B.
gavilanensis and B. luciae from the Coast Ranges of central
California. Collectively, these taxa exhibit a derived, attenuate morphology;
however, recent studies of mtDNA gene sequences (Jockusch, 1997b) support Yanev’s
(1978, 1980) finding that California slender salamanders are phylogenetically isolated
with respect to other members of the genus. For papers published prior to Yanev
(1980), it may be impossible to determine whether references to California slender
salamanders actually pertain to attenuatus or to sympatric, visually
indistinguishable (and as yet undescribed) species of the Pacific slender salamander
(B. pacificus) complex.

4. Conservation. Large portions of the historical range have been modified by
development for housing, agriculture, and other activities, although California slender
salamanders are still present over most of their original range. In some places,
such as the San Francisco Bay region, they continue to be locally abundant in urban or
suburban edge settings (e.g., gardens, vacant lots). Habitat loss is perhaps most
important in areas where the species has only a limited presence, such as the floor of
California’s Central Valley. California slender salamanders live in narrow
strips of riparian oak woodlands along small creeks draining into the Central
Valley. As modern agriculture replaces these residual habitats with drainage
ditches, the salamanders survive only by becoming symbiotic with humans (they now occur
in both Sacramento and Woodland).

Acknowledgments. We are indebted to Carla Cicero and Shawn Kuchta for
assistance with literature searches. Stephen Goldberg provided key references for
parasites. Bruce Bury and Tim Burkhardt extracted predation data from their field
notes. Richard Hoyer shared information concerning his discovery of a communal
nest.